Tubular metal bat internally reinforced with fiber and metallic composite

ABSTRACT

The bat of the present invention has a barrel with a thinner outer shell in compressive and/or adhesive engagement with an insert laminate comprised of one or more pieces of a thin metallic (preferably titanium) sheet (or foil) and one or more sheets of a composite material. The titanium portion of the insert laminate may be on the inner-most portion of the insert, may be on the outer-most portion of the laminate, or may be in the interior of the laminate (that is, with one or more sheets of composite material on either side of it). Alternatively, the bat may simply be provided with only a titanium insert. In yet another set of embodiments, the titanium sheet may be replaced by another suitable metallic sheet. In all embodiments, the reinforcing sleeve allows the barrel portion to deflect farther when impacted by an object such as a ball without detrimental yielding (denting) and increases the rate of return of the barrel wall.

[0001] This application is a continuation of Ser. No. 09/079,325 filedon May 14, 1998 and priority is claimed under 35 USC §120.

[0002] The present invention is directed to providing an improved batfor use in softball and baseball.

BACKGROUND OF THE INVENTION AND PRIOR ART

[0003] The invention relates generally to and is an improvement ofreinforced tubular metal bats such as the Easton Aluminum, Inc.(“Easton”) “C-Core” product disclosed in U.S. Pat. No. 5,364,095, whichis hereby incorporated by reference as if it were set forth herein inits entirety. Baseball and softball bats today are typically made fromaluminum or an aluminum alloy and are generally hollow inside. Such batsgenerally have a tubular outer shell comprising a barrel portion, atapered portion, and a handle portion; a knob covering the end near thehandle portion; and a cap covering the far end. Improvements in today'sbaseball and softball bats are directed to providing a wider “sweetspot,” to reducing the sting and discomfort that often results fromhitting the ball other than on the sweet spot, and to providing theseimprovements at reasonable costs and without sacrificing the bat'sdurability.

[0004] Bats have been improved by crafting the tubular outer shellentirely from titanium. This, however, raises the costs prohibitivelybecause the titanium is very expensive and difficult to form. A titaniumbat would have a retail sale price between 400 and 700 dollars.

[0005] Over the years, there have been many attempts to approach andsurpass the level of performance rendered by the titanium bat withoutthe commensurate costs. Most bat improvements today focus on the use ofinserts that reinforce the barrel portion of the tubular outer shell.The object of using reinforcing inserts is to increase the compliance(flexibility) of the bat while simultaneously controlling the stress inthe outer shell. That is, the reinforced bat is more compliant (orflexible) and can deflect more before experiencing permanent set oryield (that is, before it is dented). A more compliant bat is said toenhance player comfort and performance by reducing the amount of stingthat can be experienced during ball impact. A more compliant bat is alsosaid to have a wider “sweet spot.” The use of reinforcing inserts alsoallows the manufacturer to make the barrel portion of the outer tubularshell substantially thinner, which may tend to make the bat lighterand/or reduce its material costs. Use of an appropriate reinforcingmember in conjunction with a barrel with a thinner outer tubular shellprovides a more compliant bat because such a design allows the outershell to freely flex while offering enough modulus of elasticity(stiffness) to prevent the shell from deflecting to yield (denting).

[0006] One such approach is disclosed in the Easton U.S. Pat. No.5,364,095, which discloses a bat with a reinforced fiber or compositematerial insert in compressive engagement with the barrel's outer shell.Others have attempted to increase bat compliance in several ways.

[0007] U.S. Pat. No. 5,414,398 to Eggiman, which is hereby incorporatedby reference as if it were set forth herein in its entirety, discloses abat with a tubular insert. The outside diameter of the insert is smallerthan the inside diameter of the bat's outer shell so that there existsan annular gap between the two. The outside shell and tubular insert aretherefore able to act independently and, by so doing, together act as aleaf spring, which is said to increase bat compliance while moderatelylimiting the force required to yield (dent) the barrel portion.

[0008] U.S. Pat. No. 5,676,610 to Bhatt et al., which is herebyincorporated by reference as if it were set forth herein in itsentirety, teaches inserting a sheet of metal, wound into a spiralspring, into the bat's barrel. The sheet is of sufficient length to wrap1.1 to 3 times the inside circumference of the tubular bat barrel.

[0009] U.S. Pat. No. 5,511,777 to McNeely, which is hereby incorporatedby reference as if it were set forth herein in its entirety, teaches abat having a rebounding core therein. The McNeely bat comprises aresilient attenuator sleeve compressed between the bat's outer shell andan inner damper, fashioned from brass or a similar material. Theresilient attenuator sleeve may be fashioned from a polystyrene closedcell foam.

[0010] Despite the advances claimed in these patents, today's mostexpensive and supposedly “high performance” bats are still susceptibleto denting. Alternatively, the more durable bats are not sufficientlycompliant.

SUMMARY OF THE INVENTION

[0011] Therefore, in view of the foregoing, it is an object of thepresent invention to provide an improved bat for use in softball andbaseball.

[0012] To achieve this, the bat of the present invention has a barrelwith a thinner outer shell and an insert laminate comprised of one ormore pieces of a thin titanium sheet (or foil) and one or more sheets ofa composite material. The titanium portion of the insert laminate may beon the inner-most portion of the insert, may be on the outer-mostportion of the laminate, or may be sandwiched in the interior of thelaminate (that is, with one or more sheets of composite material oneither side of it). Alternatively, the bat may simply be provided withonly a titanium insert. In yet another set of embodiments, the titaniumsheet may be replaced by another suitable metallic sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a side view of a metallic bat.

[0014]FIG. 2 is a cross-sectional view of a standard metallic bat takenalong line 2-2 of FIG. 1.

[0015]FIG. 3 is a cross-sectional view of a bat with an insert laminate(40) taken along line 2-2 of FIG. 1.

[0016]FIG. 4 is a sectional view showing an embodiment of the presentinvention comprising, from the outside, inward, the outer shell (20), atitanium sheet (41) and two sheets of a composite material (42 a, 42 b),with layers of adhesive (43) in between.

[0017]FIG. 5 is a sectional view showing an alternative embodiment ofthe present invention comprising, from the outside, inward, the outershell (20), a first composite sheet (42 a), a titanium sheet (41) and asecond composite sheet (42 b), with layers of adhesive (43) in between.

[0018]FIG. 6 is a sectional view showing an alternative embodiment ofthe present invention comprising, from the outside, inward, the outershell (20), two sheets of a composite material (42 a, 42 b) and atitanium sheet (41), with layers of adhesive (43) in between.

[0019]FIG. 7 is a sectional view showing an embodiment of the presentinvention comprising only a titanium sheet bonded to the interior of theouter shell (20) with adhesive (43).

[0020]FIG. 8 is an embodiment of the “double-C” configuration of thepresent invention, comprising the outer shell (20) and two sheets oftitanium (41 a, 41 b).

[0021]FIG. 9 is a sectional view showing an insert laminate (40) bondedto the interior of the outer shell (20) by a series ofcylindrical-shaped portions of adhesive (43).

[0022]FIG. 10 shows an example of a net-like configuration of adhesiveto be used to accomplish partial bonding.

[0023]FIG. 11 shows an example of a cross-hatch configuration ofadhesive to be used to accomplish partial bonding.

[0024] The figures are not drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention is directed to providing an improvedmetallic bat, and in particular, to providing an improved aluminum bat.Such bats, whether for baseball or softball, generally have a tubularouter shell (20) comprising a barrel portion (21), a tapered portion(22), and a handle (23) portion; a knob (24) covering the end near thehandle (23) portion; and a cap (25) covering the far end.

[0026] Most baseball bat barrels (21) have a maximum outside diameter of2.75 inches, but some have a maximum outside diameter of 2.625 inches.Unless the bat is continuously tapered from barrel (21) to handle (23)(a constant taper), the barrel (21) will typically have a section with aconstant diameter. The constant-diameter section may range in lengthfrom near 0 inches (a constant taper) to 10-12 inches. The barrel (21)of the outer shell (20) of an aluminum baseball bat without areinforcing insert is typically from 0.105 to 0.140 inches thick.

[0027] Softball bat barrels (21) typically have a maximum outsidediameter of 2.25 inches and have a constant-diameter section that rangesin length from 8 to 18 inches. The outer shells (20) of aluminumsoftball bats without reinforcing inserts typically have a barrel (21)wall thickness between 0.070 and 0.090 inches.

[0028] In the bat of the present invention, the barrel (21) is providedwith an insert laminate (40) comprised of one or more pieces of a thinmetallic sheet (or foil) (41) and one or more sheets of a compositematerial (42). The preferred embodiment of the present invention usestitanium sheets (41) because they provide an optimal blend of highstrength and moderate modulus of elasticity (stiffness). The highstrength features of the titanium sheet (41) provides dent protectionwhile the moderate modulus of elasticity (approximately 15,000,000 psi)does not substantially impede the bat's compliance. Titanium sheets (41)as thin as 0.001 inch thick or as thick as 0.030 inches may be used,providing a large degree of control over the barrel's (21) stiffness andstrength. The titanium can be prepared for bonding directly to theinterior surface of the barrel (21) or can be used in conjunction withtraditional composite fiber reinforcing materials (e.g., graphite orcarbon, fiberglass, Kevlar™, Spectra ™, Vectran™). The insert laminate(40) may be held together strictly by compressive forces, strictly byadhesive bonding or, more preferably, by both compressive forces andadhesive bonding. Similarly, insert laminate (40) may be held againstthe interior of the outer shell (20) strictly by compressive forces,strictly by adhesive bonding or, more preferably, by both compressiveforces and adhesive bonding.

[0029] Other metals could also be used, but would likely entail designcompromises. For instance, steels, while being similar to titanium instrength, have a significantly higher modulus of elasticity (typically30,000,000 psi) which can impede the bat's compliance.

[0030] Thus, one advantage of the present invention is to bring thedesirable characteristics of titanium to bat production without thecosts of manufacturing a bat entirely or mainly from titanium. Indeed,with the present invention, costs are saved two ways: first, materialcosts are substantially reduced because only a small amount of titaniumneed be used; second, substantial production costs are saved because itis easier to use a titanium sheet insert (41) than to fashion a batentirely or mostly from titanium. It is anticipated that a bat with thetitanium insert laminate (40) of the present invention would have aretail sale price 50 percent less than would a bat fashioned all ormostly from titanium. It should also be appreciated that bat makers canuse the present invention to fashion bats with different qualities (e.g.weight, strength, flex, and size) by varying the composition of theinsert laminate (40). Thus, design flexibility is yet another advantageof the present invention.

[0031] Design flexibility is also enhanced because the bat's modulus ofelasticity (stiffness) and strength can be varied by choosing compositematerials (42) with different fiber material properties and fiberangles. For example, fiberglass epoxy systems have high straincapabilities (over 3% elongation at failure), with low modulus ofelasticity (6,000,000 psi). Graphite epoxy systems have higher strengthand modulus of elasticity than fiberglass but typically have much lowerstrain (1-1.5% elongation at failure).

[0032] Other fiber reinforcing materials (e.g. Kevlar™, Spectra™,Vectran™) have a low modulus of elasticity (<10,000,000 psi) andextremely high elongation properties (greater than fiberglass and oftentimes steel). Use of these fibers is limited due to their lowcompressive strengths and bonding strengths. Systems can be and havebeen designed using these products but the designs must compensate fortheir limited ability to carry compressive loads. Nevertheless, it willbe appreciated that bats with a wide variety of strengths andcompliances can be created by employing a variety of compositematerials.

[0033] Judicious construction of the insert laminate (40) can also offera means of damping unwanted bat vibration. Increasing the amount ofdamping can also reduce the pinging sound sometimes found objectionablein aluminum bats. For example, the fiberglass in the titanium-compositeembodiment of the present invention provides adequate damping to alterthe normal metallic “ping” sound and approximate the sound generated bya wooden bat.

[0034] First Set of Embodiments

[0035] In the most preferable set of embodiments, one or more titaniumsheets (41) are used in conjunction with one or more sheets of acomposite material (42). The titanium sheet (41) of the insert laminate(40) may be on the inner-most portion of the insert laminate (40) (e.g.FIG. 6), may be on the outer-most portion of the insert laminate (40)(e.g. FIG. 4), or may be in the interior of the insert laminate (40)(that is, with one or more sheets of composite material (42) on eitherside of it)(e.g. FIG. 5). Such structures increase the overallstress-carrying capability of the bat while providing the desired amountof compliance. The materials are preferably held together by bothcompressive forces and by adhesive bonding.

[0036] The current preferred embodiment is a bat for softball (both slowand fast pitch). The tubular aluminum bat barrel (21) has a 2.25 inchdiameter with a wall that is 0.045-0.052 inches thick, which issubstantially thinner than the wall of a traditional aluminum softballbat. A titanium sheet (41) measuring one internal circumference in width(i.e., 6.78 inches for a 0.045 inch wall; 6.74 inches for a 0.052 inchwall) by 0.009 inch thick is bonded to the aluminum barrel (21) using afilm adhesive (43) and bonding techniques well known in the art. (See,e.g. U.S. Pat. No. 5,578,384 to Kingston, which is hereby incorporatedby reference as if fully set forth herein). While the thickness of thetitanium sheet (41) is optimally 0.009 inches, it may range from0.001-0.030 inches. The length of the titanium sheet (41) is determinedby the length of the bat's constant-diameter section. See infra. Twosheets of a composite material (42 a, 42 b), preferably an S-glassfiberglass and low modulus of elasticity graphite in a toughened resinsystem (e.g. Newport 304 by Newport Adhesives & Composites, Inc.,Irvine, Calif.), are then bonded to the titanium sheet (41) by bondingtechniques such as disclosed in Easton U.S. Pat. No. 5,364,095. Thecomposite material sheets (42 a, 42 b) are cut to the same length as thetitanium sheet (41) with a width 0.10 to 0.75 inches greater than thelocal internal circumference. The thickness of each composite sheet (42a, 42 b) is optimally 0.006 inches, but can range from 0.003-0.030inches.

[0037] Use of the cure process disclosed in Easton U.S. Pat. No.5,364,095, or a similar process, generates compressive forces betweenthe layers of the insert laminate (40) and/or between the insertlaminate (40) and the outer shell (20). These compressive forces are dueto the differentials in the thermal coefficients of expansion of themetallic outer shell (20) and the materials of the insert laminate (40),and are sufficient to improve the engagement provided by adhesivebonding (43) initially applied.

[0038] The length of the titanium and composite sheets are commensuratewith the length of the constant diameter section of the bat barrel (21)minus a small section at the end of the bat for handling andcap-retention machining. In practice, most slow pitch bats have an 11inch constant diameter barrel (21) section which receive a 9-inch insertlaminate (40). The fast pitch bats with shorter constant diameter barrel(21) sections (11-13 inches) receive a 9-inch insert laminate (40) whileall the bats with longer constant diameter barrel (21) sections (14-18inches) receive a 12-inch long insert laminate (40).

[0039] While the composite sheets (42 a, 42 b) can be oriented at a widevariety of angles, the preferred embodiment employs a “+45/−45configuration.” That is, one composite sheet (42 a) is positioned at a+45 degree angle relative to the cylindrical axis of the bat, and theother composite sheet (42 b) is positioned at a −45 degree anglerelative to the cylindrical axis of the bat. Alternatively, thecomposite sheets (42 a, 42 b) should be positioned so that they are at90 degree angles with respect to each other. It will be appreciated bythose skilled in the art that use of a different composite material maynecessitate changes in the optimal configuration.

[0040] Second Set of Embodiments

[0041] In yet another set of embodiments, the insert laminate (40) isonly partially bonded to the interior of the barrel (21) (e.g. FIG. 9).Alternatively, the layers of the insert laminate (40) are only partiallybonded to each other. These embodiments enhance the bat's compliancebecause they tend to localize the force of the impact. Improvements inadhesives and bonding techniques, as well as in the strength ofcomposite materials (42) allow the partially bonded bat of the presentinvention to perform without cracking the bonding (43), cracking thecomposite material (42), or delaminating.

[0042] Various patterns of partial bonding may be used. For instance, inone embodiment, the titanium sheet (41) is bonded to the interior of thebarrel (21) by a series of cylindrical portions of adhesive (43) (e.g.FIG. 9). Any regularly repeating geometric pattern of adhesive can beadvantageously employed to improve the bat's compliance. For instance, across-hatch or net-like configuration of adhesive, such as is shown inFIGS. 10 and 11, respectively, may be used to bond the insert laminateto the interior of the barrel, or to bond the layers of the insertlaminate to each other.

[0043] Third Set of Embodiments

[0044] Yet another set of embodiments employs two or more metallic(preferably titanium) sheets (41) in a “multiple-C” configuration (e.g.FIG. 8). In a two-sheet, or “double-C” configuration, each titaniumsheet (41 a, 41 b) has a width that is greater than 50% but less than100% of the local internal circumference. The first titanium sheet (41a) is positioned radially opposite to the second titanium sheet (41 b)inside the barrel (21 ) so that at least a portion of the titaniumsheets (41 a, 41 b) overlap each other. Such a configuration isadvantageous because it allows for the use of sheets of titanium thatare thinner and narrower (in width). Such sheets are substantiallyeasier to work with than are the thicker and wider sheets. Further, useof the double-C configuration can also substantially increases the bat'scompliance.

[0045] The sheets of titanium in a double-C type configuration may bepartially or entirely bonded to the interior of the outer shell (20),and may be used in conjunction with a sheet or sheets of a compositematerial (42). Compressive forces may be used to improved the engagementof the insert laminate (40). It will be appreciated by those skilled inthe art that a “triple-C” configuration may be created by using threemetallic sheets (41), each having a width greater than 33% but less than100% of the local internal circumference. The sheets (41) in thetriple-C configuration are then positioned so that each overlaps with atleast a portion of each of the other two sheets (41). Indeed, anymultiple-C configuration created in this manner is within the scope ofthis invention.

[0046] Although the present invention has been described in considerabledetail with reference to certain preferred embodiments thereof, otherembodiments are possible. Therefore, the spirit and scope of theappended claims should not be limited to the description of thepreferred embodiments contained herein.

What is claimed:
 1. A bat, comprising: a tubular outer shell having ahandle, a barrel, and a tapered portion therebetween; and an insertlaminate at least partially bonded to the interior surface of thebarrel.
 2. The bat of claim 1, wherein said insert laminate comprisesone or more metallic sheets and one or more sheets of a compositematerial.
 3. The bat of claim 1, wherein said insert laminate comprisesone or more metallic sheets and one or more sheets of a compositematerial, said insert laminate being in compressive engagement with theinterior surface of the barrel.
 4. The bat of claim 1, wherein saidinsert laminate comprises a metallic sheet and two sheets of a compositematerial; said insert laminate being formed by bonding at least aportion of the metallic sheet to the interior surface of said outershell and subsequently bonding the composite materials to the interiorsurface of the metallic sheet in such a manner as to generatecompressive forces between said insert laminate and said outer shell. 5.The bat of claim 4, wherein the barrel is between 0.020 to 0.058 inchesthick.
 6. The bat of claim 4, wherein the barrel is between 0.045 and0.052 inches thick.
 7. The bat of claim 4, wherein the barrel has aconstant-diameter section; and wherein the length of said insertlaminate is slightly less than the length of the constant-diametersection.
 8. The bat of claim 4, wherein each sheet of composite materialis oriented at approximately 90 degree angles with respect to eachother.
 9. The bat of claim 4, wherein each sheet of composite materialis oriented at approximately 45 degree angles with respect to thecylindrical axis of the bat.
 10. The bat of claim 4, wherein saidcomposite material is an S-glass fiberglass and lowmodulus-of-elasticity graphite in a toughened resin system.
 11. The batof claim 4, wherein said composite material is Newport
 304. 12. The batof claim 4, wherein said composite material comprises reinforcing fibersin a bi-directional pattern in a resin matrix.
 13. The bat of claim 4,wherein the composite material comprises woven reinforcing fibers in abi-directional pattern in a resin matrix.
 14. The ball bat of claim 1,wherein said insert laminate is bonded to the interior surface of thebarrel by a series of cylindrical-shaped portions of bonding means, saidportions being separated from each other.
 15. The ball bat of claim 1,wherein said insert laminate is bonded to the interior surface of thebarrel by a net-like configuration of bonding means.
 16. The bat ofclaim 1, wherein said insert laminate is bonded to the interior surfaceof the barrel by a cross-hatch configuration of bonding means.
 17. Thebat of claim 1, wherein said insert laminate is bonded to the interiorsurface of the barrel by a regularly repeating geometrical configurationof bonding means.
 18. The bat of claim 2, wherein at least two of saidsheets of said insert laminate are bonded to each other by a regularlyrepeating geometrical configuration of bonding means.
 19. The bat ofclaim 2, wherein at least two of said sheets of said insert laminate arebonded to each other by a net-like configuration of bonding means. 20.The bat of claim 2, wherein at least two of said sheets of said insertlaminate are bonded to each other by a cross-hatch configuration ofbonding means.
 21. The bat of claim 1, further comprising a cap coveringthe barrel's end, and where said insert laminate is not held in itsplace by contact with said cap or with the tapered portion of said outershell.
 22. The bat of claim 1, wherein said insert laminate comprisestwo metallic sheets having a width greater than 50% but less than 100%of the barrel's local internal diameter, said sheets being positionedopposite each other.
 23. The bat of claim 1, wherein said insertlaminate comprises two metallic sheets having a width greater than 50%but less than 100% of the barrel's local internal diameter, said sheetsbeing positioned in radially opposing positions inside the barrel. 24.The bat of claim 1, wherein said insert laminate comprises threemetallic sheets having a width greater than 33% but less than 100% ofthe barrel's local internal diameter, said sheets being positionedradially inside the barrel so that at least a portion of each of saidsheets overlaps with at least a portion of each of said other twosheets.
 25. A bat as in any one of claims 2-13 inclusive, 18, 19, 20,22, 23, or 24, in which the metallic sheet is titanium.